When compiling Perl,
you must use an ANSI C compiler.
AIX does not ship an ANSI compliant C compiler with AIX by default,
but binary builds of gcc for AIX are widely available.
A version of gcc is also included in the AIX Toolbox which is shipped with AIX.

Currently all versions of IBM's "xlc",
"xlc_r",
"cc",
"cc_r" or "vac" ANSI/C compiler will work for building Perl if that compiler works on your system.

If you plan to link Perl to any module that requires thread-support,
like DBD::Oracle,
it is better to use the _r version of the compiler.
This will not build a threaded Perl,
but a thread-enabled Perl.
See also "Threaded Perl" later on.

As of writing (2010-09) only the IBM XL C for AIX or IBM XL C/C++ for AIX compiler is supported by IBM on AIX 5L/6.1/7.1.

The following compiler versions are currently supported by IBM:

IBM XL C and IBM XL C/C++ V8, V9, V10, V11

The XL C for AIX is integrated in the XL C/C++ for AIX compiler and therefore also supported.

If you choose XL C/C++ V9 you need APAR IZ35785 installed otherwise the integrated SDBM_File do not compile correctly due to an optimization bug. You can circumvent this problem by adding -qipa to the optimization flags (-Doptimize='-O -qipa'). The PTF for APAR IZ35785 which solves this problem is available from IBM (April 2009 PTF for XL C/C++ Enterprise Edition for AIX, V9.0).

If you choose XL C/C++ V11 you need the April 2010 PTF (or newer) installed otherwise you will not get a working Perl version.

Perl can be compiled with either IBM's ANSI C compiler or with gcc. The former is recommended, as not only it can compile Perl with no difficulty, but also can take advantage of features listed later that require the use of IBM compiler-specific command-line flags.

If you decide to use gcc, make sure your installation is recent and complete, and be sure to read the Perl INSTALL file for more gcc-specific details. Please report any hoops you had to jump through to the development team.

If the AIX Toolbox version of lib gdbm < 1.8.3-5 is installed on your system then Perl will not work. This library contains the header files /opt/freeware/include/gdbm/dbm.h|ndbm.h which conflict with the AIX system versions. The lib gdbm will be automatically removed from the wanted libraries if the presence of one of these two header files is detected. If you want to build Perl with GDBM support then please install at least gdbm-devel-1.8.3-5 (or higher).

Successfully tested means that all "make test" runs finish with a result of 100% OK. All tests were conducted with -Duseshrplib set.

All tests were conducted on the oldest supported AIX technology level with the latest support package applied. If the tested AIX version is out of support (AIX 4.3.3, 5.1, 5.2) then the last available support level was used.

Starting from Perl 5.7.2 (and consequently 5.8.x / 5.10.x / 5.12.x) and AIX 4.3 or newer Perl uses the AIX native dynamic loading interface in the so called runtime linking mode instead of the emulated interface that was used in Perl releases 5.6.1 and earlier or, for AIX releases 4.2 and earlier. This change does break backward compatibility with compiled modules from earlier Perl releases. The change was made to make Perl more compliant with other applications like Apache/mod_perl which are using the AIX native interface. This change also enables the use of C++ code with static constructors and destructors in Perl extensions, which was not possible using the emulated interface.

IBM uses the AIX system Perl (V5.6.0 on AIX 5.1 and V5.8.2 on AIX 5.2 / 5.3 and 6.1; V5.8.8 on AIX 5.3 TL11 and AIX 6.1 TL4; V5.10.1 on AIX 7.1) for some AIX system scripts. If you switch the links in /usr/bin from the AIX system Perl (/usr/opt/perl5) to the newly build Perl then you get the same features as with the IBM AIX system Perl if the threaded options are used.

The threaded Perl build works also on AIX 5.1 but the IBM Perl build (Perl v5.6.0) is not threaded on AIX 5.1.

Perl 5.12 an newer is not compatible with the IBM fileset perl.libext.

If your AIX system is installed with 64-bit support, you can expect 64-bit configurations to work. If you want to use 64-bit Perl on AIX 6.1 you need an APAR for a libc.a bug which affects (n)dbm_XXX functions. The APAR number for this problem is IZ39077.

If you need more memory (larger data segment) for your Perl programs you can set:

Due to the fact that AIX 4.3.3 reached end-of-service in December 31, 2003 this information is provided as is. The Perl versions prior to Perl 5.8.9 could be compiled on AIX up to 4.3.3 with the following settings (your mileage may vary):

When compiling Perl, you must use an ANSI C compiler. AIX does not ship an ANSI compliant C-compiler with AIX by default, but binary builds of gcc for AIX are widely available.

At the moment of writing, AIX supports two different native C compilers, for which you have to pay: xlC and vac. If you decide to use either of these two (which is quite a lot easier than using gcc), be sure to upgrade to the latest available patch level. Currently:

xlC.C 3.1.4.10 or 3.6.6.0 or 4.0.2.2 or 5.0.2.9 or 6.0.0.3
vac.C 4.4.0.3 or 5.0.2.6 or 6.0.0.1

note that xlC has the OS version in the name as of version 4.0.2.0, so you will find xlC.C for AIX-5.0 as package

xlC.aix50.rte 5.0.2.0 or 6.0.0.3

subversions are not the same "latest" on all OS versions. For example, the latest xlC-5 on aix41 is 5.0.2.9, while on aix43, it is 5.0.2.7.

Perl can be compiled with either IBM's ANSI C compiler or with gcc. The former is recommended, as not only can it compile Perl with no difficulty, but also can take advantage of features listed later that require the use of IBM compiler-specific command-line flags.

The IBM's compiler patch levels 5.0.0.0 and 5.0.1.0 have compiler optimization bugs that affect compiling perl.c and regcomp.c, respectively. If Perl's configuration detects those compiler patch levels, optimization is turned off for the said source code files. Upgrading to at least 5.0.2.0 is recommended.

If you decide to use gcc, make sure your installation is recent and complete, and be sure to read the Perl INSTALL file for more gcc-specific details. Please report any hoops you had to jump through to the development team.

Before installing the patches to the IBM C-compiler you need to know the level of patching for the Operating System. IBM's command 'oslevel' will show the base, but is not always complete (in this example oslevel shows 4.3.NULL, whereas the system might run most of 4.3.THREE):

AIX supports dynamically loadable objects as well as shared libraries. Shared libraries by convention end with the suffix .a, which is a bit misleading, as an archive can contain static as well as dynamic members. For Perl dynamically loaded objects we use the .so suffix also used on many other platforms.

Note that starting from Perl 5.7.2 (and consequently 5.8.0) and AIX 4.3 or newer Perl uses the AIX native dynamic loading interface in the so called runtime linking mode instead of the emulated interface that was used in Perl releases 5.6.1 and earlier or, for AIX releases 4.2 and earlier. This change does break backward compatibility with compiled modules from earlier Perl releases. The change was made to make Perl more compliant with other applications like Apache/mod_perl which are using the AIX native interface. This change also enables the use of C++ code with static constructors and destructors in Perl extensions, which was not possible using the emulated interface.

If you've chosen to use vac 4, be sure to run 4.4.0.3. Older versions will turn up nasty later on. For vac 5 be sure to run at least 5.0.1.0, but vac 5.0.2.6 or up is highly recommended. Note that since IBM has removed vac 5.0.2.1 through 5.0.2.5 from the software depot, these versions should be considered obsolete.

Here's a brief lead of how to upgrade the compiler to the latest level. Of course this is subject to changes. You can only upgrade versions from ftp-available updates if the first three digit groups are the same (in where you can skip intermediate unlike the patches in the developer snapshots of Perl), or to one version up where the "base" is available. In other words, the AIX compiler patches are cumulative.

in the "pp_ghostent" function, you may ignore it safely. The warning is caused by the reentrant variant of gethostbyaddr() having a slightly different prototype than its non-reentrant variant, but the difference is not really significant here.

In AIX 4.2 Perl extensions that use C++ functions that use statics may have problems in that the statics are not getting initialized. In newer AIX releases this has been solved by linking Perl with the libC_r library, but unfortunately in AIX 4.2 the said library has an obscure bug where the various functions related to time (such as time() and gettimeofday()) return broken values, and therefore in AIX 4.2 Perl is not linked against the libC_r.